Automotive ECU
An electronic control system (ECU) is an embedded system that controls one or more vehicle systems – from powertrain to infotainment and in modern vehicles, all systems related to driver assistance and automated driving, from sensors to actuators. ASIL D is mandatory with most domain controllers and clocks play a significant role in supporting functional safety requirements.
SiTime MEMS timing solutions provide the performance needed for automotive ECUs as E/E architectures increasingly rely on high-speed interfaces. SiTime clocks offer high accuracy, better stability over temperature, resilience to shock and vibration, and low jitter.
SiTime MEMS Timing Benefits
Complete MEMS clock treeSpread spectrum oscillators Low jitter differential oscillators 32.768-kHz XOs and TCXOs Precision TCXOs |
Most robust in real world conditions150 fs rms jitter, excellent PSNR Resistant to shock and vibration Stable over wide temperature 2.2 billion hours MTBF |
Integrated MEMS, easy to useNo quartz reliability issues Reliable startup in cold temp No cover or shielding needed Short lead time for any frequency |
Automotive ECU Block Diagram
The transition from distributed architecture in vehicles to domain architecture has a significant impact on timing. With domain architecture, the use of higher-speed interfaces places a greater need on low jitter clocks. As ECU complexity has increased, more clocks are needed. Functional safety is an integral part of today's automotive systems. ASIL D is mandatory with most domain controllers, and clocks play a significant role in supporting functional safety requirements.
MEMS Timing Solutions for Automotive ECU
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Single-ended Oscillator
SiT8924 1 to 110 MHz
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Single-ended Oscillator
SiT9025 1 to 110 MHz
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Differential Oscillators
SiT9396 1 to 220 MHz
SiT9397 220 to 920 MHz
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Super-TCXOs
SiT5386 1 to 60 MHz
SiT5387 60 to 220 MHz
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32.768 kHz Oscillator
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1 12 kHz to 20 MHz integration range
SiTime Advantages
SiTime devices offer the following benefits over quartz crystals, which are particularly important in automotive.
- 50x better reliability. Apart from reducing the amount of field failures, the better reliability translates into a lower FIT rate. This provides better hardware safety metrics in an FMEDA, the quantitative analysis required as part of a functional safety assessment.
- 100x better resilience to shock, vibration and electromagnetic interference, due to the smaller size (0.4 x 0.4 mm) and lower mass of MEMS resonators compared to crystals. When not causing a permanent damage to the crystal, shock and vibration can induce jitter in a crystal oscillator. As seen previously, jitter can be detrimental to the bit error rate of a high-speed link. Better resilience of SiTime oscillators ensures a low error rate regardless of operating conditions.
- Better frequency accuracy, 10x lower aging, and excellent stability over temperature – down to ±20 ppm (XO devices) over -40 to +125°C and ±0.1 ppm (TCXO devices) over -40 to +105°C.
MEMS Timing Outperforms Quartz
Higher Quality |
Higher Reliability |
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Tighter Stability |
Better EMI Reduction |
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Immune to Vibration |
Better Noise Rejection |
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Additional Resources
- Blog: The future of E/E architecture and its impact on timing
- Timing Solutions for Automotive Systems
- Increase automotive reliability and performance with ultra-robust MEMS oscillators
- AEC-Q100 Automotive Oscillators for ADAS Sensors, in-Vehicle Networking & Self-Driving Computer
- EMI Reduction Oscillators for Industrial, Automotive and Consumer Applications
